In a traveling-wire electroerosion machine, a thin wire, ribbon or tape, all referred to herein as "wire", is dispensed from a supply means such as a wire spool and collected into a takeup means which may also be a spool. In the path of wire travel, a pair of machining wire guide and support members are commonly provided to define therebetween a straight line path through which the electrode wire is to axially travel for electroerosively cutting a portion of a work piece located in the straight line path and flushed with a liquid machining medium such as water liquid controlled as to its conductivity or dielectricity. The electrode wire is typically composed of an electrically conductive material, e.g. of a metal such as copper or an alloy such as brass and its thickness is typically 0.1 to 1 mm. Machining feed means is also commonly provided to displace the workpiece relative to the straight line path or the axis of the traveling electrode wire transversely thereto along a predetermined feed path or machining trajectory to advance electroerosive cutting in the workpiece so that a cut of a shape corresponding to the feed path is eventually formed in the workpiece.
In conventional devices of this genre, there may take place uncontrolled transverse oscillations of the electrode wire traversing the workpiece along the straight line path between the aforementioned wire guide and support means. The occurrence of mechanical oscillations may have many causes such as, for example, the pulsation of the erosion current, the non-continuous motion of the workpiece typically incrementally fed relative to the electrode wire, and/or the impulsive character of the pressure generated in the machining zone. It has been found that these uncontrolled transverse oscillations of the traveling wire in the cutting region have a significant influence on the cutting accuracy of the electroerosion machining process. Furthermore, the uncontrolled wire oscillations tend to cause short-circuiting across the narrow cutting gap and may lead to wire breakage.
In my U.S. Pat. No. 4,205,213 issued May 27, 1980 and my prior U.S. Pat. application Ser. No. 60,346 filed July 25, 1979, (now U.S. Pat. No. 4,321,450) it has also been pointed out that transverse mechanical oscillations of the traveling wire can be positively produced and, when produced in a controlled manner by using an external vibration source, can surprisingly yield a markedly increased electroerosion removal rate without materially reducing the machining accuracy. Here again, it should be noted that any components of the oscillations in generated in an uncontrolled manner are undesirable.